Barcelona have confirmed
that Lionel Messi is undergoing further tests on kidney problems which
first emerged in December but expect the forward to return to training
on Wednesday.

The
Argentina international missed part of the Club World Cup in Japan as a
result of renal colic, an abdominal discomfort commonly caused by kidney
stones.

Reports
emerged in Spain on Monday suggesting Messi could face minor surgery in
order to correct the problem, which has reportedly persisted in recent
weeks despite the 28-year-old missing only one match since the turn of
the year.

"Leo
Messi will be submitted for different tests on Monday and Tuesday to
assess the development of the kidney problems suffered in December," a
Barcelona statement read.

"On Wednesday the player will return to training with the first team."

Messi
could be rested for the Copa del Rey semi-final second leg against
Valencia on Wednesday as Barca hold a 7-0 aggregate lead.